In general, a reception device which receives a radio signal performs signal processing by amplifying a received radio signal at an appropriate gain. In such a reception device, a gain corresponding to an amplitude of a radio signal is controlled when the amplitude of the radio signal exceeds a threshold value. The controlling is usually completed within a period of a preamble contained in the radio signal. In such a reception device, when an interference wave is received before the radio signal is received, the reception performance for the desired wave (i.e., the received radio signal) deteriorates.